Anna Faris Chris Pratt
Anna Faris (L) with her husband Chris Pratt (R) Getty

Chris Pratt took to social media to share an adorable video of his 4-year-old son Jack along with a heartfelt message on World Prematurity Day, which was celebrated on 17 November. Jack was a premature baby when The Guardians of the Galaxy actor and his wife, Anna Faris welcomed him into the world.

Although the 37-year-old actor's son was "just over 3 pounds when he was born", the little one has grown up fit and healthy with the support of March of Dimes, a nonprofit organisation that strives on improve the health of mothers and babies.

"As many of you may know, our son Jack was just over 3 pounds when he was born. Thanks to scientific advances made possible by #marchofdimes funding, today he's a perfectly healthy, curious 4 year old," Pratt wrote on Instagram.

"Today is #worldprematurityday. 15 million babies are born #prematurely each year around the world. And 1 million of them won't live to celebrate their 1st #birthday," Pratt said.

"The @marchofdimes strives for a world where every #baby has a fair chance, yet this is not the reality for many mothers and babies. Join me in supporting their efforts to give every baby a fighting chance by clicking the link in my bio. Thank you!" he concluded.

Pratt, in his speech at the non-profit organisation's luncheon in 2014, had said that after he and his wife welcomed their son he prayed the little one lived "long enough that I could keep them".

"Our Jack went from a small, helpless little squirt to a strong, smart, happy, funny, beautiful boy who loves monster trucks and Daniel Tiger, and, believe it or not, loves vegetables," Pratt had said. (Via E!News) "Broccoli and cherry tomatoes are his favorite foods."